Remove support for NPObjects.

content/child/npapi/npobject_base.h

-// Copyright 2013 The Chromium Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-//
-// Base interface used by NPChannelBase and implemented by NPObjectProxy and
-// NPObjectStub.
-
-#ifndef CONTENT_CHILD_NPAPI_NPOBJECT_BASE_H_
-#define CONTENT_CHILD_NPAPI_NPOBJECT_BASE_H_
-
-#include "ipc/ipc_listener.h"
-#include "third_party/npapi/bindings/npruntime.h"
-
-struct NPObject;
-
-namespace content {
-
-class NPObjectBase {
- public:
-  virtual ~NPObjectBase() {}
-
-  // Returns the underlying NPObject handled by this NPObjectBase instance.
-  virtual NPObject* GetUnderlyingNPObject() = 0;
-
-  // Returns the channel listener for this NPObjectBase instance.
-  virtual IPC::Listener* GetChannelListener() = 0;
-};
-
-}  // namespace content
-
-#endif  // CONTENT_CHILD_NPAPI_NPOBJECT_BASE_H_